METHOD FOR MANUFACTURING A VESSEL AND A DOUBLE-WALL TANK

Abstract

A method for manufacturing a vessel configured for housing a fluid within, the method including: providing at least two at least partially cured fiber reinforced polymer (FRP) structures with complementary shapes configured for matching with each other such that an interior volume is defined when the at least partially cured FRP structures are coupled to each other; coupling the at least partially cured FRP structures to each other such that the interior volume is defined; winding at least one layer of FRP material onto at least a portion of the at least partially cured FRP structures once coupled to each other; and applying a curing cycle to cure the resulting assembly.

Claims

1. A method for manufacturing a vessel configured for housing a fluid within, the method comprising: a) providing at least two at least partially cured fiber reinforced polymer (FRP) structures shaped with complementary coupling interfaces configured to match with each other, such that an interior volume is defined when the at least partially cured FRP structures are coupled to each other to form an assembly; b) coupling the at least partially cured FRP structures to each other such that the interior volume is defined; c) winding at least one layer of FRP material onto at least a portion of the at least partially cured FRP structures once coupled to each other; and d) curing the assembly resulting from step c).

2. The method according to claim 1 further comprising, before step a), manufacturing each at least partially cured FRP structure by applying a partial curing cycle, at least one of: at a lower temperature compared to a temperature adapted to complete a curing cycle according to which the FRP structures are completely cured, or a shorter duration compared to a duration adapted to complete a curing cycle according to which the FRP structures are completely cured.

3. The method according to claim 2 further comprising, before applying the partial curing cycle, laying up a laminate comprising FRP plies over a mold by Automated Fiber Placement or Automatic Tape Laying techniques.

4. The method according to claim 2 further comprising, before applying the partial curing cycle: laying-up an ensemble formed by a honeycomb core and, at least on one side on the honeycomb core, from the inside to the outside of the honeycomb core: a curable adhesive layer and an amorphous thermoplastic film; laying-up a dry fiber layer over the ensemble; arranging the dry fiber layer and ensemble on a one-sided mold and confining it in a gas-tight space by arranging a vacuum sheet over the one-sided mold; and infusing the dry fiber layer under vacuum with resin.

5. The method according to claim 1, wherein at least one at least partially cured FRP structure provided in step a) comprises at least one of at least one baffle or wall-type element projecting from an inner surface of the at least partially cured FRP structure towards the interior volume defined when the at least partially cured FRP structures are coupled to each other according to step b).

6. The method according to claim 1, wherein two at least partially cured FRP structures provided in step a) are dome-shaped FRP structures, each dome-shaped FRP structure having a convex outer side and a concave inner side.

7. The method according to claim 6, wherein an at least partially cured cylindrical FRP structure is provided in step a); wherein the two dome-shaped FRP structures comprise circular flanges projecting from each respective concave inner side; and wherein the at least partially cured cylindrical FRP structure is sized with a diameter less than or substantially equal to the diameter of the circular flanges of each dome-shaped FRP structure, such that each dome-shaped FRP structure and the at least partially cured cylindrical FRP structure are coupled to each other with a tight fit according to step b), with the circular flanges overlapping a border of the at least partially cured cylindrical FRP structure.

8. The method according to claim 6, wherein at least one of the dome-shaped FRP structures is provided with at least one breakthrough hole configured for allowing insertion of tubing and for establishing a fluidic communication between the inside and the outside of the vessel.

9. The method according to claim 1, wherein at least one partially cured FRP structure provided in step a) is dome-shaped having a convex outer side and a concave inner side, and a thickness of the dome-shaped FRP structure progressively increases from the coupling interface to a polar area of the dome-shaped FRP structure.

10. A method for manufacturing a double-wall tank configured for housing a fluid within, the method comprising: i) providing a vessel manufactured according to claim 1; ii) providing at least two at least partially cured fiber reinforced polymer (FRP) tank structures shaped with complementary coupling interfaces configured for matching with each other, such that an interior chamber is defined when the at least partially cured FRP tank structures are coupled to each other, the interior chamber being sized for housing the vessel provided in step i), such that a gap is defined between the outer side of the vessel and the inner side of the at least partially cured FRP tank structures when the vessel is housed within the interior chamber; iii) coupling the at least partially cured FRP tank structures to each other enclosing the vessel provided in step i) within; wherein at least a spacer is provided between the outer side of the vessel and the inner side of the at least partially cured FRP tank structures for maintaining the at least partially cured FRP tank structures at a predetermined distance from the vessel; iv) winding at least one layer of FRP material onto at least a portion of the at least partially cured FRP tank structures once coupled to each other to form an assembly; and v) curing the assembly resulting from step iv).

11. The method according to claim 10 further comprising, before step iii), providing at least a thermal insulation layer enveloping the vessel.

12. The method according to claim 10, further comprising, before step ii), manufacturing each at least partially cured FRP tank structure by applying a partial curing cycle at a lower temperature and/or shorter duration compared to a complete curing cycle under predetermined duration and temperature conditions at which the FRP tank structures are completely cured.

13. The method according to claim 12 further comprising, before applying the partial curing cycle, laying up a laminate formed by FRP plies provided over a mold by Automated Fiber Placement or Automated Tape Laying techniques.

14. The method according to claim 12, further comprising, before applying the partial curing cycle: laying-up an ensemble formed by a honeycomb core and, at least on one side on the honeycomb core, from the inside to the outside: a curable adhesive layer and an amorphous thermoplastic film; laying-up a dry fiber layer over the ensemble; arranging the dry fiber layer and ensemble on a one-sided mold and confining it in a gas-tight space by arranging a vacuum sheet over the one-sided mold; and infusing the dry fiber layer under vacuum with resin.

15. A method for manufacturing a double-wall tank configured for housing a fluid within, the method comprising: a) providing a vessel manufactured according to claim 1; b) providing an outer wall defining an interior chamber sized for housing the vessel provided in step a), such that a gap is defined between the outer side of the vessel and the inner side of the outer wall when the vessel is housed within the interior chamber.

16. The method according to claim 15, wherein the outer wall provided in step b) is an FRP structure manufactured by Automated Fiber Placement or Automated Tape Laying techniques.

17. The method according to claim 15, wherein step b) comprises providing at least two inner FRP tank structures shaped with complementary coupling interfaces configured for matching with each other, such that the interior chamber is defined when the inner FRP tank structures are coupled to each other, such that a gap is defined between the outer side of the vessel and the inner side of the inner FRP tank structures when the vessel is housed within the interior chamber; coupling the inner FRP tank structures to each other enclosing the vessel provided within; wherein at least a spacer is provided between the outer side of the inner vessel and the inner side of the inner FRP tank structures for maintaining the inner FRP tank structures at a predetermined distance from the inner vessel; providing at least two outer FRP tank structures shaped with complementary coupling interfaces configured for matching with each other, such that a sheathing is defined when the outer FRP tank structures are coupled to each other, the sheathing being sized for encasing the inner FRP tank structures, contacting them on their outer surface, after they have been coupled to each other; coupling the outer FRP tank structures to each other, encasing the inner FRP tank structures, such that a relative position of the inner FRP tank structures is locked thereby; and fastening the outer FRP tank structures after they have been coupled to each other.

18. A method for manufacturing a double-wall tank configured for housing a fluid within, the method comprising: i) providing a vessel; ii) providing at least two at least partially cured FRP tank structures shaped with complementary coupling interfaces configured for matching with each other, such that an interior chamber is defined when the at least partially cured FRP tank structures are coupled to each other, the interior chamber being sized for housing the vessel provided in step i), such that a gap is defined between the outer side of the vessel and the inner side of the at least partially cured FRP tank structures when the vessel is housed within the interior chamber; iii) coupling the at least partially cured FRP tank structures to each other enclosing the vessel provided in step i) within; wherein at least a spacer is provided between the outer side of the vessel and the inner side of the at least partially cured FRP tank structures for maintaining the at least partially cured FRP tank structures at a predetermined distance from the vessel; iv) winding at least one layer of FRP material onto at least a portion of the at least partially cured FRP tank structures once coupled to each other to form an assembly; and v) curing the assembly resulting from step iv).

19. The method according to claim 18, wherein the vessel provided in step i) is a FRP structure manufactured by Automated Fiber Placement or Automated Tape Laying techniques.

20. The method according to claim 18, wherein step i) comprises providing at least two inner FRP structures shaped with complementary coupling interfaces configured for matching with each other, such that an interior volume is defined when the inner FRP structures are coupled to each other; coupling the inner FRP structures to each other; providing at least two outer FRP structures shaped with complementary coupling interfaces configured for matching with each other, such that a sheathing is defined when the outer FRP structures are coupled to each other, the sheathing being sized for encasing the inner FRP structures, contacting them on their outer surface, after they have been coupled to each other; coupling the outer FRP structures to each other, encasing the inner FRP structures such that a relative position of the inner FRP structures is locked thereby; and fastening the outer FRP structures after they have been coupled to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0140] These and other characteristics and advantages of the invention will become clearly understood in view of the detailed description of the invention which becomes apparent from a preferred embodiment of the invention, given just as an example and not being limited thereto, with reference to the drawings.

[0141] FIG. 1 shows a perspective view of two at least partially cured FRP structures provided according to steps of a method for manufacturing a vessel according to an embodiment of the present invention.

[0142] FIG. 2 shows a perspective view of three at least partially cured FRP structures steps coupled together and wrapped with a layer of FRP material enveloping the at least partially cured FRP structures according to steps of a method for manufacturing a vessel according to an embodiment of the present invention.

[0143] FIG. 3 shows a perspective view of three at least partially cured FRP structures steps coupled together and wrapped with a layer of FRP material enveloping the at least partially cured FRP structures according to steps of a method for manufacturing a vessel according to an embodiment of the present invention.

[0144] FIG. 4 shows a perspective view of two at least partially cured FRP tank structures provided around a vessel according to steps of a method for manufacturing a double-wall tank according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0145] The present invention provides a method for manufacturing a vessel (10) configured for housing a fluid within.

[0146] This method comprises at least the following steps: [0147] a) providing at least two at least partially cured Fiber Reinforced Polymer (FRP) structures (11, 12) shaped with complementary coupling interfaces (11.1, 12.1) configured for matching with each other, such that an interior volume is defined when the at least partially cured FRP structures (11, 12) are coupled to each other; [0148] b) coupling the at least partially cured FRP structures (11, 12) to each other such that the interior volume is defined; [0149] c) winding at least one layer (13) of FRP material onto at least a portion of the at least partially cured FRP structures (11, 12) once coupled to each other; and [0150] d) curing the assembly resulting from step c).

[0151] FIG. 1 shows some of the manufacturing steps that the present method follows to obtain a vessel (10) according to an embodiment. Particularly, FIG. 1 shows the provision of two closed hemicylindrical at least partially cured FRP structures (11, 12) according to step a), the FRP structures (11, 12) comprising a cylindrical central portion with two spherical portions located at the opposite ends of the cylindrical central portion. More in particular, both FRP structures (11, 12) are complementary and, once coupled, they define a capsule-type structure closed at its ends by means of respective spherical cap portions.

[0152] In the particular embodiment shown, both hemicylindrical structures (11, 12) have been previously manufactured by applying a partial curing cycle at a lower temperature and/or shorter duration compared to a complete curing cycle under predetermined duration and temperature conditions according to which the FRP structures (11, 12) are completely cured.

[0153] With respect to the layup techniques carried out for obtaining the preform of each FRP structure (11, 12) prior to the application of the partial curing cycle, according to different embodiments of the above method, the layup techniques may be one of the following:

[0154] Laying up a laminate formed by FRP plies provided over a mold by Automated Fiber Placement (AFP) or Automated Tape Laying (ATL) techniques.

[0155] Laying-up an ensemble formed by a honeycomb core and, at least on one side on the honeycomb core, from the inside to the outside: a curable adhesive layer and an amorphous thermoplastic film; laying-up a dry fiber layer over the ensemble; arranging the dry fiber and ensemble on a one-sided mold and confining it in a gas-tight space by arranging a vacuum sheet over the one-sided mold; and infusing the dry fiber layer under vacuum with resin.

[0156] As it can be seen in FIG. 1, each hemicylindrical structure (11, 12) comprises two wall-type elements (14) projecting from each corresponding inner surface towards the cylindrical interior volume defined when the hemicylindrical structures (11, 12) are coupled to each other according to step b) of the above method.

[0157] In the particular embodiment shown, the wall-type elements (14) are anti-sloshing walls.

[0158] As previously described, the sloshing motion of the fluid housed within the vessel (10) can induce significant structural loads and rigid body disturbances which may affect control system operation. The presence of the anti-sloshing walls (14) installed within the inner volume of the vessel (10), extending inwardly from an inner surface helps to attenuate sloshing of the fluid.

[0159] The anti-sloshing walls (14) are depicted having complementary geometries. In particular, the anti-sloshing walls (14) shown are divided into two halves which are respectively provided on opposite surfaces of different hemicylindrical structures (11, 12), in such a way that, when the hemicylindrical structures (11, 12) are coupled according to step b), the complementary anti-sloshing walls (14) are arranged in a particular cross-section of the vessel (10), facing each other and separated a distance in such a way that their opposite contours define a nearly rectangular gap for allowing the fluid housed within the vessel (10) to flow therethrough.

[0160] With respect to the layup techniques carried out for providing the anti-sloshing walls (14) on the inner surface of each hemicylindrical structure (11, 12), an embodiment of the method of the invention comprises, before applying the partial curing cycle: laying up a corresponding laminate forming each anti-sloshing wall (14) over the hemicylindrical structure (11, 12), the laminate being laid up preferably by ATL or AFP techniques.

[0161] According to another embodiment, FIG. 2 shows some of the manufacturing steps of the present method. FIG. 2 shows some of the manufacturing steps that the present method follows to obtain a vessel (10) according to an embodiment. Particularly, FIG. 2 depicts a longitudinal cross-sectional view of a vessel (10) showing the provision of two dome-shaped FRP structures (11, 12) according to step a) of the above method.

[0162] As it can be seen in the embodiment shown, each dome-shaped FRP structure (11, 12) comprises a convex outer side and a concave inner side, the concave inner side being oriented towards the interior volume of the vessel (10) after all the at least partially cured FRP structures (11, 12, 15) have been coupled to each other according to step b).

[0163] An additional at least partially cured FRP structure (15) is provided according to step a). As it can be seen, at least partially cured cylindrical FRP structure (15) is coupled to the two dome-shaped FRP structures (11, 12). In particular, the two dome-shaped FRP structures (11, 12) comprise circular flanges (16) projecting from each respective concave inner side. The at least partially cured cylindrical FRP structure (15) is sized with a diameter less than or substantially equal to the diameter of the circular flanges (16) of each dome-shaped FRP structure (11, 12).

[0164] As it can be seen, each dome-shaped FRP structure (11, 12) is coupled to a different end of the at least partially cured FRP cylindrical structure (15) with a tight fit according to step b), with the circular flanges (16) overlapping the border of the at least partially cured cylindrical FRP structure (15).

[0165] As with the hemicylindrical structures (11, 12) of FIG. 1, the two dome-shaped FRP structures and the at least partially cured FRP cylindrical structure (15) have been previously manufactured by applying a partial curing cycle at a lower temperature and/or shorter duration compared to a complete curing cycle under predetermined duration and temperature conditions according to which the three FRP structures (11, 12, 15) are completely cured.

[0166] With respect to the layup techniques carried out for obtaining the preform of each FRP structure (11, 12, 15) prior to the application of the partial curing cycle, according to different embodiments of the above method, the layup techniques may be one of the following:

[0167] Laying up a laminate formed by FRP plies provided over a mold by Automated Fiber Placement (AFP) or Automated Tape Laying (ATL) techniques.

[0168] Laying-up an ensemble formed by a honeycomb core and, at least on one side on the honeycomb core, from the inside to the outside: a curable adhesive layer and an amorphous thermoplastic film; laying-up a dry fiber layer over the ensemble; arranging the dry fiber and ensemble on a one-sided mold and confining it in a gas-tight space by arranging a vacuum sheet over the one-sided mold; and infusing the dry fiber layer under vacuum with resin.

[0169] In the embodiment of the method shown in FIG. 2, step b) comprises providing a suction cup and/or adhesive film at the coupling interfaces (11.1, 12.1) between each dome-shaped FRP structure (11, 12) and the at least partially cured cylindrical FRP structure (15).

[0170] FIG. 2 also shows the provision in one dome-shaped FRP structure (11) of several breakthrough holes (17) through which a plurality of pipes (17.1) are inserted for the provision and extraction of fluid into and from the interior of the vessel (10).

[0171] A fluid level sensor in the form of an optical guide is also shown arranged inside the vessel (10) represented by a dashed line.

[0172] Finally, the embodiment shown in FIG. 2 also represents the provision, according to step c), of a layer (13) of FRP material enveloping the at least partially cured FRP structures (11, 12, 15) once coupled to each other according to step b). In particular, the resulting assembly is shown entirely wrapped by the layer (13) which, according to different embodiments of the method of the invention, can be provided preferably by Automated Fiber Placement (AFP), or by filament winding techniques. For illustrative purposes, the layer (13) of FRP material is represented with a dashed line surrounding the contour whole vessel (10).

[0173] In an alternative embodiment, step a) comprises providing one at least partially cured dome-shaped FRP structure and one at least partially cured cylindrical FRP structure which is closed at one of its ends by a spherical portion; wherein the dome-shaped FRP structure is coupled to the open end of the at least partially cured cylindrical FRP structure according to step b), the resulting geometry of the vessel (10) being identical to that of the vessel (10) shown in FIG. 2.

[0174] FIG. 3 shows an embodiment similar to that of FIG. 2. In particular, in the same manner as in FIG. 2, FIG. 3 depicts a longitudinal cross-sectional view of a vessel (10) showing the provision of two dome-shaped FRP structures (11, 12) according to step a) of the above method.

[0175] As it can be seen in the embodiment shown, each dome-shaped FRP structure (11, 12) is coupled to a different end of the at least partially cured FRP cylindrical structure (15) with a tight fit according to step b).

[0176] However, in the embodiment shown in FIG. 3, it can be seen that the thickness of the dome-shaped FRP structure (11) which is provided with several breakthrough holes (17) through which a plurality of pipes (17.1) is inserted, progressively increases from the coupling interface with the at least partially cured FRP cylindrical structure (15) to the polar area of the dome-shaped FRP structure (11).

[0177] Advantageously, structural reinforcement is achieved in the polar area of the vessel (10) through which the plurality of pipes (17.1) is inserted.

[0178] In this regard, the embodiment shown in FIG. 2 also represents the provision, according to step c), of two layers (13, 13′) of FRP material enveloping the at least partially cured FRP structures (11, 12, 15) once coupled to each other according to step b). In particular, the resulting assembly is shown comprising the two layers (13), which for illustrative purposes are represented with dashed lines, surrounding the coupling interfaces between each dome-shaped FRP structure (11, 12) and the at least partially cured cylindrical FRP structure (15).

[0179] Thereby, the weight of the vessel (10) may be optimized by winding FRP material only at specific areas of the vessel (10) at which the FRP structures (11, 12, 15) are joined to each other.

[0180] The present invention also provides a method for manufacturing a double-wall tank (20) configured for housing a fluid within.

[0181] This method comprises: [0182] i) providing a vessel (10) manufactured according to one of the methods described above; [0183] ii) providing at least two at least partially cured fiber reinforced polymer (FRP) tank structures (21, 22) shaped with complementary coupling interfaces (21.1, 22.1) configured for matching with each other, such that an interior chamber is defined when the at least partially cured FRP tank structures (21, 22) are coupled to each other, the interior chamber being sized for housing the vessel (10) provided in step a), such that a gap is defined between the outer side of the vessel (10) and the inner side of the at least partially cured FRP tank structures (21, 22) when the vessel (10) is housed within the interior chamber; [0184] iii) coupling the at least partially cured FRP tank structures (21, 22) to each other enclosing the vessel (10) provided in step a) within; wherein at least a spacer (24) is provided between the outer side of the vessel (10) and the inner side of the at least partially cured FRP tank structures (21, 22) for maintaining the at least partially cured FRP tank structures (21, 22) at a predetermined distance from the vessel (10); [0185] iv) winding at least one layer (23) of FRP material onto at least a portion of the at least partially cured FRP tank structures (21, 22) once coupled to each other; and [0186] v) curing the assembly resulting from step iv).

[0187] FIG. 4 shows some of the manufacturing steps that the present method follows to obtain a double-wall tank (20) according to an embodiment. Particularly, FIG. 4 shows the provision of a vessel (10) according to step i), as well as the provision of two hemicylindrical at least partially cured FRP tank structures (21, 22) according to step ii).

[0188] In the particular embodiment shown, both hemicylindrical tank structures (21, 22) have been previously manufactured by applying a partial curing cycle at a lower temperature and/or shorter duration compared to a complete curing cycle under predetermined duration and temperature conditions according to which the hemicylindrical tank structures (21, 22) are completely cured.

[0189] With respect to the layup techniques carried out for obtaining the preform of each FRP tank structure (21, 22) prior to the application of the partial curing cycle, according to different embodiments of the above method, the layup techniques may be one of the following:

[0190] Laying up a laminate formed by FRP plies provided over a mold by Automated Fiber Placement (AFP) or Automatic Tape Laying (ATL) techniques.

[0191] Laying-up an ensemble formed by a honeycomb core and, at least on one side on the honeycomb core, from the inside to the outside: a curable adhesive layer and an amorphous thermoplastic film; laying-up a dry fiber layer over the ensemble; arranging the dry fiber and ensemble on a one-sided mold and confining it in a gas-tight space by arranging a vacuum sheet over the one-sided mold; and infusing the dry fiber layer under vacuum with resin.

[0192] The embodiment of a double-wall tank (20) manufactured by the method of FIG. 4 also comprises a thermal insulation layer (not shown) enveloping the vessel (10) provided in step i). The thermal insulation layer is arranged in the space confined between the inner wall of the tank (i.e., the vessel (10)) and the outer wall of the tank (20). In an embodiment, the method comprises maintaining the thermal insulation layer in a vacuum.

[0193] Furthermore, in order to define an intermediate gap disposed around the vessel (10), between its outer side and the outer wall of the tank (20), a plurality of spacers (24) are provided onto the outer surface of the vessel (10) for maintaining the outer wall of the tank (20) (which in the particular example shown in FIG. 4 is formed by the two hemicylindrical at least partially cured FRP tank structures (21, 22)) at a predetermined distance from the inner vessel (10).

[0194] As it can be seen, the spacers (24) are embodied as a plurality of discrete mechanical spacers (24) provided with a rectangular cross-section and distributed around the vessel (10).

[0195] Finally, the embodiment shown in FIG. 4 also represents the provision, according to step IV), of a layer (23) of FRP material enveloping the hemicylindrical tank structures (21, 22) once coupled to each other according to step iii). In particular, the resulting assembly is shown partially wrapped by the layer (23) which, according to different embodiments of the method of the invention, can be provided preferably by Automated Fiber Placement (AFP), or by filament winding techniques. For illustrative purposes, the layer (23) of FRP material is represented with parallel grey stripes over one hemicylindrical tank structure (21).

[0196] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.